Jupiter		Topics	Posts	Last Posts
	Europa Smallest, yet only natural life-capable Jovian moon. At just over 3,100 kilometres (1,900 mi) in diameter, Europa is slightly smaller than Earth's Moon and is the sixth-largest moon in the Solar System. It is primarily made of silicate rock and likely has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably serve as an abode for extraterrestrial life. Heat energy from tidal flexing ensures that the ocean remains liquid and drives geological activity.	0	0
	Io Third largest Jovian moon. With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's interior by Jupiter's varying pull. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of the moon's silicate crust. Unlike most satellites in the outer Solar System (which have a thick coating of ice), Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is characterized by extensive plains coated with sulfur and sulfur dioxide frost.	0	0
	Ganymede The Largest Jovian Moon bigger than both Earth's Moon and Mercury. Ganymede is composed primarily of silicate rock and water ice. It is a fully differentiated body with an iron-rich, liquid core. A saltwater ocean is believed to exist nearly 200 km below Ganymede's surface, sandwiched between layers of ice. Its surface comprises two main types of terrain. Dark regions, saturated with impact craters and dated to four billion years ago, cover about a third of the satellite. Lighter regions, crosscut by extensive grooves and ridges and only slightly less ancient, cover the remainder. The cause of the light terrain's disrupted geology is not fully known, but was likely the result of tectonic activity brought about by tidal heating.	0	0
	Callisto The Second Largest Jovian Moon. Callisto is composed of approximately equal amounts of rock and ices, with a mean density of about 1.83 g/cm3. Compounds detected spectrally on the surface include water ice, carbon dioxide, silicates, and organics. Investigation by the Galileo spacecraft revealed that Callisto may have a small silicate core and possibly a subsurface ocean of liquid water at depths greater than 100 kilometers.	0	0